U01.07.022 Wolff-Parkinson-White syndrome

Wolff-Parkinson-White (WPW) syndrome is the most common type of ventricular preexcitation syndrome. It is characterized by an abnormal accessory conduction pathway, known as the bundle of Kent, which allows electrical impulses to bypass the normal conduction delay at the atrioventricular (AV) node. This results in early depolarization of the ventricles, leading to specific ECG findings and potential arrhythmias.

Pathophysiology

An accessory conduction pathway (bundle of Kent) directly connects the atria and ventricles, bypassing the AV node.
This causes preexcitation of the ventricles, leading to early partial depolarization.
The altered conduction pattern creates a reentry circuit, which can result in supraventricular tachycardia (SVT).

Electrocardiogram (ECG) Findings

WPW syndrome is diagnosed based on characteristic ECG changes:

ECG Feature	Description
Delta wave	Slurred upstroke of the QRS complex, indicating early ventricular activation.
Widened QRS complex	Due to early activation of the ventricles via the accessory pathway.
Shortened PR interval	Less than 120 ms, as impulses bypass the AV node, reducing normal delay.

Clinical Implications

WPW can predispose patients to paroxysmal supraventricular tachycardia (PSVT) due to reentrant circuits.
In some cases, it can lead to atrial fibrillation (AF) with rapid ventricular response, which may cause hemodynamic instability.

Management

Acute SVT episodes: Vagal maneuvers, adenosine, or beta-blockers (avoid AV nodal blockers like digoxin and calcium channel blockers in atrial fibrillation cases).
Definitive treatment: Catheter ablation of the accessory pathway to prevent recurrence.

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